Thermionic valve



May 17, 1932. L. J. DAVIES TH ERMIONIC VALVE Filed Dec. 12, 1928 Ifivehtor: Leonard J. Davies,

His Attorney,

Patented May 17, 1932 I asers LEONARD J; Dawns, or RUGBY, ENGLAND, .assxcnon "ro man/an nnnotrnrccdm rAnY a-oonrona'rron or NEWYORK I j I ranged on either side of the cathode.

THERMIONIG vii-Lyn Application filed December 12, 1 928, Serial No. 325,632, and in Great Britain December 13,-1927.

This invention relates to thermionic valves in which the self-capacity between the anode and controlelectrode' is substantially eliminated by means of anadditional screen electrode in the form of'a grid which'is disposed between the control grid and the anode, which screen: electrode is maintained ata fixed potential, usually of a value somewhat lower than that of the anode.

The object of this invention is to provide a construction for such valves which will enable better operating constants to be obtained, and which will simplify the manufacture thereof. 7

The invention consists in forming the anode as a flat plate which is surrounded on both sides by the screen electrode shaped as a flattened cylinder.

In carrying the invention into eifect, the anode may consist of a single plate arranged on one side of a filamentary cathode in the form of a V, or of two parallel plates ar- In both cases the screen electrode preferably consists of a wire wound helically about two supporting wires lying in the plane of the anode, or of each section thereof, so that the screen is closely spaced therefrom. The control elec trode may also consist of a wire grid in the form of a flattened cylinder surrounding the cathode. Where a single plate is employed as anode, the control electrode may be a flat or curved wire grid arranged between the cathode and the screen electrode, but the flattened cylindrical construction is also preferably employed in this case since the manufacture of this form of grid is perhaps more simple. The several electrodes may be supported by wires which are sealed into the usual press or pinch, and certain of these wires may be employed to conduct the necessary current or potential to the electrodes. The leading-in wire for the control electrode, however, is preferably led out of the enclosing envelope through the end remote from the pinch, as by this means the capacity between the control electrode and the anode is still further reduced.

If it be desired to construct a valve in which a third grid is used either immediately'next to the filament or between the screen-grid and the anode in order to improve the operating constants of the valve ortoj ensure stability in operation, thenthe; method of con. struction described is still preferred, the third grid may be interposed either as a plane! member situated between. the control-grid and the screen-grid or as awire'fgrid in the form of a' flattened cylinder c'oaiiial with the screen grid; i

electrode construction iii accordance with the invention is illustrated in the ac'coiiie pa'nylfng drawings i which Fi 1 ice; perr' spectivevifew, ile Fig. 2 is a diagrammatic View ofa modified construction.

an the construction illustrated a sin-git plate-shade 'i is supported by a leading in wire 2 sealed intoi a pinch 3' and e'x'tends in a direction p'arallelto the; mainaxis offlle enclosing nvei pe 4: of the device. v Sunrounding the anode a screen consistin .0f' a" helicalwire grid 5 in the for'rifof a -attened cylinder; This grid rsisu ported by two wires 6 and extending parallel to the" edges of he anode'fand attached to: a meat he lates, which closes the end or the screen electrode nearest the pinch angina-s an s arth through which 'the anode lead passes}, and is supported by" a lead wire (not shown) sealed into the pin h. This plate manifessired, have depending flaps 9 which assi t in protecting the, pinch roin electron bomb'ardfni'ent, and increase the shielding elfect. or the'scre'en' electrode; The other end of the screen; electrod reattached totlie screen sup ort-wires, which 3 also have short" wire i 11: welded to, them, i which wire, areembdded in a glass rod or head head also carries a; hoolr113 p gthe tighter; sly-shap d filal r cathode f4, which is disposed paral for support-1n mentzrr e is al o cussed 15y a'plat'e le'l tat fe anode. a d; has its ends attached to,

leadsalso sealed into the pinch. also in the head are short wires15 which support a wire" grudrical' hape which Winds and iqrms the chntroi grrid, As'wij11jhe db.- server from the draw ngs; the; control meniber is positioned y the anode? A lea'd 1'7"00 this grids-sealed" Embedded,

ity still further.

embedded in an into the end of the envelope remote from the pinch, so as to reduce the anode-grid capac- Nickel or molybdenum may be used for the various support wires employed, while nickel is preferably used for the anode and the other metallic plates employed in this construction.

In the modified construction shown in Fig. 2 the electrodes are in part supported by a rectangular framework, consisting of a metal plate 21, preferably of nickel or molybdenum, and two metallic wires 22 attached to one end to the plate, and having their other ends insulating member 23', prefg erably a glass rod, arranged parallel to the plate, which is itself supported by wires sealed into a glass press or pinch. A filamentary cathode 24 of V shape has its bight supported by a metallic hook 25 sealed into the glass rod and its two ends supported by le'ading-in'wires 26 which project through holes in the metal plate, and which are sealed into the pincln The control grid which immediately surrounds the cathode isin the form of a flattened cylinder 27 supported by stifl wires 28 lying in the plane of the filament, which are sealed into or otherwise sup-V ported by the glass rod. The anode consists oftwo parallel rectangular plates 29' of nickel 'that for'the or the likewhich are supported by wires 30, only one of which is shown, sealed into the pinchandelectrically connectedto one another These plates are arranged on opposite sides of the cathode,to which they are parallel. Surrounding each anode plate is a grid 31 of flattened cylindrical shape which is closely spaced therefrom. These grids are. electrically connected and constitute the screen electrode; They'are each supported by wires '32 lying in the plane of each anode plate and close to the edges thereof, these wires being attached to the frame plate, which thus constitutes an integral part of the screen electrode and greatly assists in screening the anode from the control grid. One of the supi port wires for the frame plate is taken through the pinch, andv permits of an operating potential being suppliedto the screen electrode." The'leads to the anode and cathode are alsotaken through the pinch, but control electrodeis taken through trol grid in said device for cooperating with said cathode and anode, said control grid and cathode being'positionedi between said anode members." I

3. An electron discharge device comprising an electron emitting cathode, an anode consisting of a plurality of flat members, screen grids in the form of flattened cylinders surrounding said members, and a control grid in said device for cooperating with said cathode and anode,

said control. gridsurrounding the cathode and being positioned jinterme diate said anode members.

In witness whereof, I have hereunto set my hand this 20th day of November, 1928..

LEONARD J-. DAVIES,

' fob the other end of'the enclosing envelope, for V the'reasonstated above.

V The construction describedmay be more readily manufacturedthan previous constructions of valves the characteristic curve otthe' valve may be 7 made to conform more closely'to a desired by Letters Patent of the outline" i I a 'What'I claim as new and desire to secure United States is: '1. electron discharge device comprising an electron emittingcathode, an anode consisting of a plurality of flat ;members,- screen grids in the form of flattened cylin-.

with screen electrodes, and,

F an 

